Simon Gerrans has taken five seconds out of fellow Australian Cadel Evans' overall lead at the Tour Down Under.
Gerrans followed through on his pledge to take the contest up to Evans, winning one intermediate sprint and finishing second in the other during Friday's fourth stage of the cycling tour.
German sprint ace Andre Greipel (Lotto-Belisol) scored his 15th Tour stage win when he took the 148.5km stage from suburban Unley to Victor Harbor, south of Adelaide.
Gerrans was fourth and, if he was one place higher in the high-speed finish, he would have picked up another four bonus seconds.
There were nervous moments for Evans at the second intermediate sprint near the finish when he suffered a mechanical problem, putting him out of contention to go up against Gerrans for time bonuses.
He then had to change his bike, but quickly returned to the peloton.
Evans (BMC) took the overall lead from Gerrans (Orica-GreenEDGE) with an outstanding solo win in Thursday's third stage.
Friday's action sets up an absorbing weekend of racing that will decide the Tour title.
Stage five on Saturday at Willunga, south of Adelaide, is always crucial and features a summit finish.
Gerrans was runner-up there two years ago to set up his second overall title and won the stage last year.
The Tour could come down to bonus seconds on Sunday in the final stage, a street race through the Adelaide CBD.
German Marcel Kittel (Giant Shimano) was expected to contest the Victor Harbor sprint, but he was in a second main group that finished several minutes behind the peloton.
Gerrans won the first intermediate sprint, picking up three bonus seconds, and was runner-up in the second to gain another two seconds.
Fourth-placed Nathan Haas (Garmin Sharp) finished third in the first sprint and won the second sprint to gain four time bonus seconds.
There was a flurry of attacks early in Friday's stage and eventually a five-rider break went clear after the first sprint.
Australian Cameron Wurf (Cannondale) and French rider Axel Domont (Ag2r) went clear of the other three members of the breakaway and built a lead of nearly five minutes.
But the peloton were never going to let them stay away ahead of the second intermediate sprint.
Crosswinds created tricky conditions for the bike riders and several, including British star Geraint Thomas (Sky), almost came to grief.
Thomas briefly went off onto the side of the road before recovering and returning to the peloton.